1. Field of the Invention
The present invention relates to synchronizing revolute joints. Such synchronizing revolute joints, which are designed, for example, for use in motor vehicles, are also referred to as homokinetic revolute joints.
2. Description of Related Technology
A state-of-the-art synchronizing revolute joint is known from DE 102 06 733 A1 (commonly owned by the Assignee of the present application), the subject matter of which is fully incorporated into the disclosure of the present application by reference. The synchronizing revolute joint disclosed therein comprises a bell-shaped external joint member with three circumferentially arranged and axially extending tracks. In the external joint member there is arranged an internal joint member with three circumferentially arranged and radially extending pivots, which include a bearing surface for a rolling bearing. The pivots are arranged to engage the tracks in the external joint member. For this purpose, rolling bearings are arranged between the external joint member and the internal joint member, each rolling bearing including an inner race with a rolling bearing inner surface, the shape of the inner surface being adapted to the bearing surface of the pivots for the rolling bearing so as to enable the pivot of the internal joint member inserted into the inner race to perform therein a tilting motion, but not a linear displacement motion. The rolling bearing further including an outer race with a rolling bearing outer surface, the shape of the outer surface being adapted to the tracks of the external joint member so as to enable an outer race inserted into the tracks to perform therein a linear displacement motion, but not a tilting motion.
A retaining ring is pressed into an outer race and the ring includes two radially inwardly extending peripheral flanges. Between the peripheral flanges there is positioned a set of rollers, which as needle bearings. An inner race supports the inner surface of the rollers, the length of the rollers being greater than the width of the inner race and the width of the outer race. This design allows a relatively large axial displacement or shift between the inner race and the rollers, the inner race being supported on the rollers over its entire width within the track independently of the fixed position of the outer race and being movable in order to keep its suitable position in relation to the pivot when the pivot swings inside it. In connection with the present invention, this type of rolling bearing is referred to as “dynamic bearing”.
The construction which is known from DE 102 06 733 A1 (corresponding to U.S. Pat. No. 6,99,134, which is herein incorporated by reference) provides particular advantages with respect to low friction and the vibrationless operation of the synchronizing revolute joint. A disadvantage of that construction is, however, the relatively costly design of the rolling bearings, which increases the manufacturing costs of the synchronizing revolute joint.
It is therefore the object of the present invention to provide a synchronizing revolute joint that is of a simplified design and thus reduces the manufacturing costs, while maintaining the positive antifrictional qualities of the synchronizing revolute joint mentioned above.
According to an embodiment of the present invention, a synchronizing revolute joint is provided having an external joint member with three circumferentially arranged and axially extending tracks. Within the external member there is arranged an internal joint member with three circumferentially arranged and radially extending pivots, each of which includes a bearing surface for a rolling bearing. The pivots are arranged to engage the tracks in the external joint member. Rolling bearings are arranged between the external joint member and the internal joint member. The rolling bearings each include an inner race with a rolling bearing inner surface, the shape of said surface being adapted to the bearing surface of the pivots for the rolling bearing so as to enable the pivot of an internal joint member inserted into the inner race to perform therein a tilting motion, but not a linear displacement motion. The rolling bearings further include an outer race with a rolling bearing outer surface, the shape of said surface being adapted to the tracks of the external joint member so as to enable an outer race inserted into the track to perform therein a linear displacement motion, but not a tilting motion. Between the inner and outer races are arranged a plurality of rollers enabling the outer race to roll on the inner race.
According to one aspect of the present invention, the inner and outer races are axially displaceable against each other, the inner race including an axial guide that determines the position of the rollers in relation to the inner race in the axial direction. In an alternative embodiment, the outer race includes an axial guide that determines the position of the rollers in relation to the outer race in the axial direction.
In a preferred embodiment of the synchronizing revolute joint, the inner race or the outer race includes a stop limiting the relative axial displaceability of the inner and outer races, at least in one direction of displacement. In this way the rolling bearing can be reliably prevented from falling apart during the final assembly of the synchronizing revolute joint according to the present invention or when the assembled joint is pivoted at extreme angles. It is particularly advantageous to have the stop on that race of the rolling bearing which does not comprise the axial guide for the rollers. It is particularly preferred to have the stop on that side of the rolling bearing which, in the assembled state of the synchronizing revolute joint, faces the center of the tripod star.
It is particularly advantageous for the wear resistance of the rolling bearing if the stop is formed on the outer race and the outer contour of the inner race does not project over it, if the axial guide for the rollers is formed in the inner race. On the other hand, it is particularly advantageous if the stop is formed on the inner race and the inner contour of the outer race does not project over it, if the axial guide for the rollers is formed in the outer race. In both cases the stop abuts the rotating rollers and not the other race of the rolling bearings when there is a maximal axial displacement of the races against each other. This considerably reduces the occurring friction.